Some of diagnostic agents and diagnostic kits for diagnosing diseases such as cancer and infectious diseases use a solid-phase carrier such as magnetic particles. Such solid-phase carrier usually binds a ligand such as an antibody or oligonucleotide and is used. For example, the antibody and oligonucleotide specifically bind to, for example, a specific antigen or nucleic acid. Thus, for example, the presence or absence and concentration of a diagnostic marker in a sample can be detected. Also, it is possible to isolate, for example, specific cells such as cancer cells, by the same method.
With the improvement and development of a solid-phase carrier, detection sensitivity has been improved year by year, and the detectable diagnostic markers and the kind of cells that can be isolated have been increased. For example, Patent Literature 1 describes carrier particles of which surface is covered with a polymer layer that can bind to a probe. This polymer is constituted by a monomer unit having a carboxy group on a side chain and a monomer unit having a 2, 3-dihydroxypropyl group on a side chain.
In addition, Patent Literature 2 describes a multiblock vinyl polymer, i.e., polymer particles in which a block copolymer binds to the surface.